JP2561352B2 - Automatic tuning receiver - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Overview Radio receivers and the like having an automatic tuning tuner function have been in widespread use from the past. In the present invention, the signal meter voltage, which is the DC voltage corresponding to the received electric field strength of the received signal received by the receiver, is directly input to the microcomputer through the input port. At the time of setting the search sensitivity, the receiver is set to the receiving state by the received signal having the predetermined received electric field strength, and the signal output at the time of the reception is made by a simple operation only by operating the search sensitivity setting switch. Store the meter voltage in memory. The store sets the threshold level of the received electric field strength during frequency scanning of the automatic tuning tuner function, the signal meter voltage input corresponding to the received signal received during frequency scanning, and the memory. The frequency scan stop time is determined by comparing with the threshold level stored in the. In this way, the search sensitivity is simply adjusted and variations in the search sensitivity among products are eliminated.

FIELD OF THE INVENTION The present invention relates to an automatic tuning receiver such as a radio receiver having an electronic tuning type tuner function.

2. Description of the Related Art Conventionally, in an on-vehicle radio receiver or the like, while automatically scanning a reception frequency, a value corresponding to a reception electric field strength of a reception signal is discriminated from a predetermined threshold value, and as a result, When a reception electric field strength corresponding to a value larger than a threshold value is obtained, the so-called automatic tuning tuner function is provided, which stops the scanning at the reception frequency of the reception signal having the reception electric field strength and puts the reception circuit in the reception state. Tend to be.

FIG. 5 is a block diagram showing a simplified configuration of the receiver 1 showing a typical first conventional example. FIG. 5 shows the configuration of a frequency modulation (FM) receiver as an example. A received signal received from the antenna 2 is amplified and tuned by a high frequency signal component via a front end circuit 3, mixed with an oscillation signal from a local oscillation circuit provided in association therewith, and given to an intermediate frequency amplification circuit 4. . The intermediate frequency amplification circuit 4 tunes and amplifies the intermediate frequency signal component and supplies it to the detection circuit 5. The detection circuit 5 generates a detection output based on the signal from the intermediate frequency amplification circuit 4, and outputs a signal meter voltage SM0 which is a DC voltage corresponding to the received electric field strength of the received reception signal. The signal meter voltage SM0 is given to a signal conversion circuit 10 provided in association with the detection circuit 5, and the detection output is sonicated from a speaker 7 via a low frequency amplifier circuit 6 in which the miute is released.

The control circuit 8 is provided in association with the receiving circuit having the above configuration and controls the operation of the receiving circuit. In particular, the control circuit 8 includes a frequency dividing circuit, a phase comparing circuit, a reference signal generating circuit, and the like, and a phase lock circuit and a local oscillating circuit included in the front end circuit 3 are used for phase locking. A droop circuit is configured. When the automatic tuning tuner function is activated by an input operation on the input means 9 such as a key matrix provided in association with the control circuit 8, the phase-locked loop circuit functions and the reception circuit receives the signal. Initiate automatic scanning of possible reception frequencies.

The signal meter voltage SM0 output from the detection circuit 5 to the signal conversion circuit 10 is divided by the variable resistor 11 and the resistors 12 and 13 connected in series from the output end of the variable resistor, and the transistor 14 Given to the base of. By adjusting the variable resistor 11, a predetermined threshold value of the signal meter voltage SM0 is set, and the transistor 14 is turned on / off according to the received electric field strength of each receiving frequency during scanning. Thus, the collector potential of the transistor 14 connected from the drive voltage line via the resistor 15 is
It is switched to a high level / low level and is given to the control circuit 8 as a search stop signal SD0 called a so-called station detector. Therefore, when the search stop signal SD0 is switched from the high level to the low level during scanning of the reception frequency by the automatic tuning type tuner function, the reception signal of the reception electric field strength larger than the predetermined threshold value is generated. When it is determined that it has been obtained, the scanning of the reception frequency is stopped and the reception circuit is set to the reception state.

FIG. 6 is a block diagram showing the configuration of a typical second conventional receiver 1a. In FIG. 6, the same or corresponding parts as in FIG. 5 are designated by the same reference numerals. Receiving machine
In 1a, the detection circuit 5a is configured by an integrated circuit, and generates a detection output according to the intermediate frequency signal component given from the intermediate frequency amplification circuit 4a, and directly performs the search according to the received electric field strength. Generate stop signal SD0,
Output to the control circuit 8. That is, no configuration for adjusting the signal meter voltage SM0 is provided.

In the receiver 1a, the amplification degree of the intermediate frequency amplifier circuit 4a is adjusted by the variable resistor 18. That is, by adjusting the variable resistor 18, the amplification degree of the intermediate amplification circuit 4a is adjusted, and thus the detection signal is supplied to the detection circuit 5a and detected.
The received electric field strength of the intermediate frequency signal component whose level is discriminated from the predetermined threshold is amplified. Therefore, the amplification degree is adjusted so that the lower limit of the reception electric field strength that should be receivable matches the threshold value. Even with such a configuration, when a reception signal having a reception electric field strength equal to or higher than a predetermined threshold is obtained during the scanning of the reception frequency by the automatic tuning tuner function, the search stop signal is output from the detection circuit 5a. SD0 is given to the control circuit 8, and thus the scanning of the reception frequency is stopped and the reception circuit is set to the reception state.

As described above, in the configuration of the typical prior art receivers 1 and 1a, the reception electric field strength is level-discriminated by the automatic tuning tuner function, that is, the search sensitivity. The setting is performed by manually adjusting the variable resistors 11 and 18 which are independently arranged outside the receiving circuit. These adjustments are necessary to absorb variations in the characteristics of the individual components that make up the receiving circuit for each product, and are performed by the manufacturer at the manufacturing stage. As a result, the search sensitivity varies from product to product depending on the skill level of the manufacturer, resulting in deterioration of product quality. Further, the adjustment is very complicated and the workability is poor.

Therefore, it is an object of the present invention to provide an automatic tuning receiver capable of adjusting the search sensitivity without variation among products by a simple operation.

Means for Solving the Problems The present invention provides an automatic tuning receiver having a search function for scanning a reception frequency, a memory for storing a value corresponding to an electric field strength of an arbitrary reception frequency by a predetermined operation, and the memory. The automatic tuning is characterized by comprising a control means for scanning the reception frequency by using the stored value as a threshold for comparing the electric field strength and controlling the scanning to stop when the electric field strength larger than the value stored in the memory is detected. It is a receiver.

Operation According to the present invention, when setting the search sensitivity in the automatic tuning receiver having the search function for operating the reception frequency, the reception electric field strength that becomes a threshold value of an arbitrary reception frequency is set by, for example, a setting operation switch. The memory can be stored only by a simple operation.
In addition, since the threshold value is stored in the memory according to the unique characteristics of the receiving circuit, it is possible to set the search sensitivity to the same level for each product, thus eliminating the variation in the search sensitivity and further improving the skill level of the manufacturer. There is no variation depending on the situation.

Embodiment 1 FIG. 1 is a block diagram showing a simplified configuration of a receiver 21 which is an embodiment of the present invention. The receiver 21 has a configuration of an FM receiver or an amplitude modulation (AM) receiver, and the configuration will be described below.

The received signal received from the antenna 22 has a high-frequency signal component tuned and amplified through a front-end circuit 23, mixed with an oscillation signal from a local oscillator circuit (not shown) provided in the front-end circuit 23, and then intermediate-frequency amplified. Provided to circuit 24. The intermediate frequency amplifier circuit 24 tunes and amplifies the input intermediate frequency signal component, and the detection circuit 25
Give to. The detection circuit 25 generates a detection output based on the signal from the intermediate frequency amplification circuit 24 and outputs a signal meter voltage SM which is a DC voltage component corresponding to the received electric field strength of the received signal. The detection circuit
The detection output from 25 is a low frequency amplifier circuit that can solve the miute.
It is given to the speaker 27 via 26 and made into sound.

The receiving circuit having a series of configurations from the antenna 22 to the speaker 27 is controlled by a control circuit 28 including, for example, a microcomputer. A phase locked loop circuit is formed in the control circuit 28 between the control circuit 28 and the front end circuit 23 in order to perform the self-tuning tuner function. The oscillation signal from the local oscillation circuit configured in the front end circuit 23 controls the tuning function for the high frequency signal component of the received signal,
It is given to the frequency dividing circuit 30 via the input port 29 of the control circuit 28.

In the frequency dividing circuit 30, a processing circuit provided in the control circuit 28.
The oscillation signal is frequency-divided according to the frequency division ratio N given from 31 and is given to one input of the phase comparison circuit 32. A reference signal having a predetermined frequency is applied to the other input of the phase comparison circuit 32 from the reference signal generation circuit 33, and a signal corresponding to the phase difference between the inputs is supplied to the digital / analog conversion circuit 3.
4, the output port 35 of the control circuit 28, and the low-pass filter formed in the front-end circuit 23, to the local oscillation circuit. In this way, the frequency division circuit 30, the phase comparison circuit 32, the reference signal generation circuit 33, and the digital / analog conversion circuit 34 constitute the phase locked loop partial circuit 36, and further the front end circuit 23 is included in the phase locked loop. Make a circuit.

In connection with the processing circuit 31, for example, a RAM (Random Ac
cess Memory) and EEPROM (Electrically Erasable Progr
A memory 37 including an amable read only memory) is provided. In the memory 37, a value for a predetermined threshold value for the received electric field strength which becomes the search sensitivity in the manufacturing stage is stored.

Further, the processing circuit 31 determines a signal corresponding to an input operation by an operator in the input means 32 including a key matrix, and executes various functions.

In the present embodiment, the signal meter voltage SM output by the detection circuit 25 is given to the analog / digital conversion circuit 40 via the input port 39 of the control circuit 28. In the analog / digital conversion circuit 40, the signal meter voltage is digitally converted and given to the processing circuit 31. In the processing circuit 31, the signal meter voltage applied to the processing circuit 31 when the search sensitivity setting switch 41, which is a setting operation switch provided in the input means 38, is operated.
The SM is stored in the memory 37 as the threshold SMt.

When scanning the reception frequency by the automatic tuning type tuner function, the processing circuit 31 outputs the frequency division ratio N to the frequency division circuit 30,
While operating the phase locked loop circuit, the signal meter voltage SM input corresponding to the received signal received is compared with the threshold value SMt stored in the memory 37. As a result of the comparison, when the threshold value SMt is larger than the input signal meter voltage SM, the frequency division ratio N is updated and a reception signal is received at a new reception frequency. Thus, as a result of the comparison, the input signal meter voltage SM
Is equal to or more than the threshold value SMt, it is determined that a reception signal having a predetermined reception electric field strength or more is obtained, and the processing circuit 31 fixes and outputs the frequency division ratio N when the reception signal is obtained. In this way, the receiving circuit is set to the receiving state at the receiving frequency when the scanning was stopped.

Therefore, the setting of the threshold value SMt which is the search sensitivity is executed only by a simple operation of operating the search sensitivity setting switch 41. Further, since the signal meter voltage serving as the threshold SMT is stored in the memory 37 while receiving the reception signal having the predetermined reception electric field strength, the variation in the threshold depending on the proficiency of the manufacturer may occur for each product. The same search sensitivity can be set for each product.

The operation of the receiver 21 is displayed by the display means 42 such as a liquid crystal display device and is visually recognized by the operator.

When the search sensitivity setting switch 41 is used only in the search sensitivity setting at the manufacturing stage, it may be equipped inside the receiver so that it is not operated by a general operator, and a general operation is performed. In the case where the person is allowed to freely set the search sensitivity, the other switches may coexist outside the receiver.

FIG. 2 is a flow chart for explaining the search sensitivity setting operation. Threshold value SM of the signal meter voltage which is the search sensitivity in the program manufacturing stage shown in FIG.
Executed when setting t.

In step s1, a reception signal having a reception electric field strength at the lower limit of the range of the reception electric field strength to be receivable is supplied to the antenna 22, and the reception circuit is set to the reception state. Step s2
Then, in the reception state, the search sensitivity setting switch 41
At step s3, the signal meter voltage SM, which is input from the detection circuit 25 through the input port 39 of the control circuit 28 and is digitally converted, is set to the threshold value SM in step s3.
It is stored in the memory 37 as t, and this program ends. Thus, the search sensitivity can be set to be the same for each receiver by a simple operation.

FIG. 3 is a flow chart for explaining the receiving frequency selecting operation by the automatic tuning type tuner function. In step m1, when the operator scans a scan start switch (not shown) or the like by the input means 38, the scanning of the reception frequency is started, the frequency division ratio N is updated in step m2, and the processing circuit in step m3. Detection circuit 25 input to 31
And compares the signal meter voltage SM from 1 to the threshold value SMt stored in the memory 37 by the setting operation. As a result of the comparison, the input signal meter voltage SM is equal to the threshold SM.
When it is less than t, the process returns to step m2, the frequency division ratio N is newly updated, and the receiving circuit is set to the receiving state at the new receiving frequency. In this way, the processes of steps m2 and m3 are repeated, and when it is determined that the input signal meter voltage SM is equal to or higher than the threshold value SMt, the process proceeds to step m4, and the updating of the frequency division ratio N is stopped. That is, it is judged that the received signal having a predetermined received electric field strength or more is obtained, the receiving circuit is set to the receiving state according to the receiving frequency when the updating is stopped, and the program is terminated.

In the selecting operation, after step m2, the processing circuit 31 determines whether or not the signal meter voltage SM is input.If the determination is negative, the process returns to step m2, and the determination is made. If is positive, the process may proceed to step m3.
According to the program configuration, when the signal meter voltage is not detected, that is, when there is no received signal, the frequency division ratio N is immediately updated and the scanning speed is improved.

FIG. 4 is a block diagram showing a simplified configuration of a receiver 21a which is another embodiment of the present invention. In the above-described embodiment, the receiver 21 has the configuration of a receiver capable of receiving either the FM signal or the AM signal. by the way,
The receiver 21a capable of receiving both FM and AM can also be equipped with the configuration of this embodiment. In FIG. 4, the same or corresponding parts as in FIG. 1 are designated by the same reference numerals.

The FM detection unit 50 that detects the FM signal is an FM front end circuit.
23a, the FM intermediate frequency amplifier circuit 24a, further comprises the FM detection circuit 25a, the AM detection unit 51 for detecting the AM signal,
For example, an AM detection integrated circuit consisting of a one-chip integrated circuit
It is composed by 45. The AM detection integrated circuit 45 has an FM
The components such as the front-end circuit and the intermediate frequency amplifier circuit that form the detector 50 are integrally included. The outputs of the FM detection section 50 and the AM detection section 51 are selectively mixed by the mixing circuit 46, and are sonicated from the speaker 27 via the low frequency amplification circuit 26.

The control circuit 28 includes a phase-locked loop circuit similar to that shown in FIG. 1. The phase-locked loop circuit is individually configured by the FM detection unit 50 and the AM detection unit 51. The tuned tuner function can be executed. The FM detection circuit 25a outputs an FM signal signal meter voltage SM FM, and the AM detection integrated circuit 45 outputs an AM signal signal meter voltage SM AM. The signal meter voltages SM FM and SM AM are applied to the input port 39 of the control circuit 28 via the backflow preventing diodes 47 and 48, respectively.

In this way, a receiver that can receive FM and AM signals
In 21a, each threshold value is stored in the memory 37 by using the signal meter voltage from the detection unit provided individually for each signal, and during the scanning of the reception frequency by the automatic tuning tuner function, the above-mentioned store is performed. The reception frequency may be selected by performing a comparison operation with the threshold thus set. Therefore, the search sensitivity can be set by an easy operation, and the variation of each product can be absorbed.

When the voltage range of the signal meter voltage is wide, the scanning of the reception frequency may stop at the wrong frequency. Therefore, in addition to the signal meter voltage SM, the search stop signal described in the related art may also be used to AND the signal meter voltage SM and the search stop signal. In this way, the determination at the time of scanning is performed by, for example, comparing the threshold value stored in the memory after the search stop signal designating the stop of the scanning is input with the signal meter voltage input. Even if the voltage range of the signal meter voltage is wide, it is possible to avoid erroneous stoppage of scanning at another frequency due to an erroneous situation.

EFFECTS OF THE INVENTION According to the present invention, when the search sensitivity is set, it can be realized by a simple operation of receiving a reception signal of a predetermined reception electric field strength and operating, for example, a setting operation switch. No need for adjustment work. Also, the configuration circuit is simple, and it can be realized at a low price and in a small space.

Further, since the search sensitivity is set according to the peculiar characteristic of each product, it is possible to set the search sensitivity to the same level for each product without causing variations due to the skill level of the manufacturer. Yes, the quality is improved.

[Brief description of drawings]

FIG. 1 is a block diagram showing a simplified configuration of a receiver 21 which is an embodiment of the present invention, FIG. 2 is a flow chart for explaining a search sensitivity setting operation, and FIG. 3 is an automatic tuning type tuner function. 4 is a flow chart for setting the receiving frequency selecting operation in FIG. 4, FIG. 4 is a block diagram showing a simplified configuration of a receiver 21a which is another embodiment of the present invention, and FIG.
FIG. 6 is a block diagram showing a simplified configuration of a receiver 1 which is a typical first conventional example, and FIG. 6 is a block diagram showing a simplified configuration of a receiver 1a which is a typical second conventional example. is there. 21 ... Receiver, 22 ... Antenna, 23 ... Front-end circuit, 24 ... Intermediate frequency amplification circuit, 25 ... Detection circuit, 28 ...
… Control circuit, 36… Phase lock loop circuit,
37 …… Memory, 39 …… Input port, 41 …… Search sensitivity setting switch, SM …… Signal meter voltage, SMT …… Threshold

Claims (1)

(57) [Claims] 1. An automatic tuning receiver having a search function for scanning a reception frequency, a memory for storing a value corresponding to an electric field strength of an arbitrary reception frequency by a predetermined operation, and an electric field strength for the value stored in the memory. The automatic tuning receiver is characterized by further comprising: a control unit configured to scan the reception frequency as a threshold value for the comparison and control to stop the scanning when an electric field strength larger than a value stored in the memory is detected.